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Stern tube alterations

Posted: Mon Apr 15, 2019 7:06 pm
by Colin chandler
Shortening a brass/ bronze stern tube,
Does anyone know what thread is used on stern tubes? Is it a BSP ?
Where can I get my tube re threaded after I've cut it down?
Regards Colin Southend on sea Essex

Re: Stern tube alterations

Posted: Mon Apr 15, 2019 7:59 pm
by RGSP
Colin,
the bad news is that the thread could be any of several things. The good news is that cutting a new thread should be easy enough, whatever it is. You need to make an accurate measurement of the thread outer diameter, and the pitch, and that should be enough to identify a new thread which will fit, even if the thread shoulder angle isn't quite correct. If the tube is out of the boat, putting it in a medium-to-large lathe is the back-up option, though if it is a BSP thread, getting and industrial plumber to do it should be cheaper and easier.

If you get stuck, contact me directly: I'm a few miles north of the Essex-Suffolk border.

Re: Stern tube alterations

Posted: Mon Apr 29, 2019 8:13 pm
by Colin chandler
So far I've discovered it's an inch and five eights , I'm waiting for some pitch gauges to turn up.

Re: Stern tube alterations

Posted: Wed May 01, 2019 7:43 pm
by Colin chandler
My gauges have arrived and it seams its a 12 G whitworth thread an inch and five eights